* It's a local or homemade game: The name "Thunder" might be used for a game specific to a certain region or group of friends.
* It's a misremembered name: You might be thinking of a different game with a similar name.
* It's a new game: Perhaps the game is very recent, and rules haven't been widely publicized yet.
To find the rules, you could try:
* Ask the people you learned the game from: If you know who taught you how to play, they might be able to provide the rules.
* Search online with more specific details: Try searching for "dice game Thunder" along with additional keywords like the location where you learned the game, the number of players, or any specific mechanics you remember.
* Check game forums and communities: There are online forums dedicated to board games and dice games. Posting a description of the game might help you find others who know it.
Good luck in your search!